Electrosurgical forceps with stamped double-flange jaws and u-shaped drive actuation mechanism

ABSTRACT

A surgical instrument includes a housing that supports an elongated shaft. A selectively movable drive rod extends through the elongated shaft and carries a cam pin in a longitudinal direction. An end effector for surgically treating tissue is supported by the elongated shaft and includes upper and lower jaw members pivotally coupled to one another about a pivot axis. The upper jaw member includes a first pair of laterally spaced flanges, and the lower jaw member includes a second pair of laterally spaced flanges defining a camming slot for engaging the cam pin. The flanges are arranged in an offset configuration where one flange of the upper jaw member is positioned on a laterally exterior side of a corresponding flange of the lower jaw member, and the other flange of the upper jaw member is positioned on a laterally interior side of the other flange of the lower jaw member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/604,385 filed on Jan. 23, 2015, now U.S. Pat. No. 9,375,263, which isa continuation of U.S. patent application Ser. No. 13/461,378 filed onMay 1, 2012, now U.S. Pat. No. 8,968,311, the entire contents of each ofwhich are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to the field of surgicalinstruments. In particular, the disclosure relates to an endoscopicelectrosurgical forceps that is economical to manufacture and is capableof sealing and cutting relatively large tissue structures.

2. Background of Related Art

Instruments such as electrosurgical forceps are commonly used in openand endoscopic surgical procedures to coagulate, cauterize and sealtissue. Such forceps typically include a pair of jaws that can becontrolled by a surgeon to grasp targeted tissue, such as, e.g., a bloodvessel. The jaws may be approximated to apply a mechanical clampingforce to the tissue, and are associated with at least one electrode topermit the delivery of electrosurgical energy to the tissue. Thecombination of the mechanical clamping force and the electrosurgicalenergy has been demonstrated to join adjacent layers of tissue capturedbetween the jaws. When the adjacent layers of tissue include the wallsof a blood vessel, sealing the tissue may result in hemostasis, whichmay facilitate the transection of the sealed tissue. A detaileddiscussion of the use of an electrosurgical forceps may be found in U.S.Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodesdisposed on clamping faces of the jaws. The electrodes are charged toopposite electrical potentials such that an electrosurgical current maybe selectively transferred through tissue grasped between theelectrodes. To effect a proper seal, particularly in relatively largevessels, two predominant mechanical parameters must be accuratelycontrolled; the pressure applied to the vessel, and the gap distanceestablished between the electrodes.

Both the pressure and gap distance influence the effectiveness of theresultant tissue seal. If an adequate gap distance is not maintained,there is a possibility that the opposed electrodes will contact oneanother, which may cause a short circuit and prevent energy from beingtransferred through the tissue. Also, if too low a force is applied thetissue may have a tendency to move before an adequate seal can begenerated. The thickness of a typical effective tissue seal is optimallybetween about 0.001 and about 0.006 inches. Below this range, the sealmay shred or tear and above this range the vessel walls may not beeffectively joined. Closure pressures for sealing large tissuestructures preferably fall within the range of about 3 kg/cm2 to about16 kg/cm2.

SUMMARY

The present disclosure describes a surgical instrument for treatingtissue that is economical to manufacture and is capable of sealing andcutting relatively large tissue structures. The surgical instrumentincludes a housing and an elongated shaft extending distally therefrom.The elongated shaft includes a proximal portion coupled to the housingand a distal portion opposite the proximal portion, and defines alongitudinal axis. A drive rod extends at least partially through theelongated shaft, and is selectively movable in a longitudinal directionwith respect to the elongated shaft. A cam pin is supported by the driverod such that longitudinal movement of the drive rod is imparted to thecam pin. An end effector is supported by the distal portion of theelongated shaft, and is adapted for treating tissue. The end effectorincludes an upper jaw member pivotally coupled to the distal portion ofthe elongated shaft about a pivot axis, and the upper jaw memberincludes a first pair of laterally spaced flanges each defining acamming slot for engaging the cam pin. The end effector also includes alower jaw member pivotally coupled to the distal portion of theelongated shaft about the pivot axis, and the lower jaw member includesa second pair of laterally spaced flanges each defining a camming slotfor engaging the cam pin. The first and second pairs of flanges of thejaw members are arranged in an offset configuration such that one flangeof the upper jaw member is positioned on a laterally exterior side of acorresponding flange of the lower jaw member, and the other flange ofthe upper jaw member is positioned on a laterally interior side of theother flange of the lower jaw member.

The upper and lower jaw members may be constructed as substantiallyidentical components positioned in a laterally offset manner withrespect to one another. Each of the flanges may extend proximally from atissue engaging portion of the jaw members, and the tissue engagingportions may be substantially curved. The pivot axis may extends througheach of the flanges in a direction substantially transverse to thelongitudinal axis.

The drive rod may extend through the jaw members on a laterally interiorside of each of the flanges, and the drive rod may exhibit a generallyu-shaped profile. The surgical instrument may further include a knifeselectively movable in a longitudinal direction with respect to thedrive rod, and the knife may be supported within the u-shaped profilesuch that the drive rod provides restricts lateral movement of the knifein a first lateral plane. The drive rod may also include an overfolddisposed opposite a u-shaped connector portion of the drive rod suchthat the knife is substantially surrounded on four lateral sides, andsuch that the overfold and the u-shaped connector portion restrictmovement of the knife in a second lateral plane that is orthogonal tothe first lateral plane.

The jaw member may be adapted for electrosurgically treating tissue andmay include electrical wires extending proximally therefrom forfacilitating connection of the respective jaw members to a source ofelectrosurgical energy. At least one of the flanges of each of the jawmembers may include an electrically isolative wire guide disposed on alateral side thereof, wherein the electrical wire of the respective jawmember extends through the wire guide. The wire guides may beconstructed of an electrically isolative plastic molded onto therespective flanges.

According to another aspect of the disclosure a surgical instrumentincludes a housing and an elongated shaft extending therefrom. Theelongated shaft includes a proximal portion coupled to the housing and adistal portion opposite the proximal portion and defining a longitudinalaxis. An end effector is supported by the distal portion of theelongated shaft. The end effector is adapted for treating tissue andincludes first and second jaw members pivotally coupled to one anotherto move between open and closed configurations. Each of the jaw membersincludes a pair of laterally spaced flanges, and each of the flangesincludes a camming surface thereon. A knife extends at least partiallythrough the elongated shaft and is selectively movable in a longitudinaldirection between the flanges of the jaw members. A blade of the knifeis extendable into a tissue contacting portion of the jaw members. Adrive rod extends at least partially through the elongated shaft and isselectively movable in a longitudinal direction with respect to theknife and with respect to the elongated shaft in response tomanipulation of the housing. The drive rod carries a cam pin positionedto engage the camming surface of each of the flanges to induce the jawmembers to move between the open and closed configurations. The driverod substantially surrounds the knife on four lateral sides to restrictmotion of the knife in at least two orthogonal planes.

The laterally spaced flanges of the jaw members may be arranged in anestled configuration wherein both of the flanges of one of the jawmembers are arranged within a laterally interior side of the laterallyspaced flanges of the other of the jaw members. The knife may beconstructed of a substantially flat piece of metal, and the drive rodmay be constructed of metal folded to exhibit a generally u-shapedprofile extending around the four lateral sides of the knife. Adistal-most end of the drive rod may extend around the four lateralsides of the knife and a proximal portion of the drive rod may extendaround fewer than four lateral sides of the knife.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is a perspective view of an electrosurgical forceps according toan embodiment of the present disclosure including a housing, anelongated shaft, and an end effector;

FIG. 2A is an enlarged perspective view of the end effector of FIG. 1depicted with a pair of jaw members in an open configuration;

FIG. 2B is an enlarged perspective view of the end effector of FIG. 1depicted with the pair of jaw members in a closed configuration;

FIG. 3 is a perspective view of the end effector and elongated shaft ofFIG. 1 with parts separated;

FIG. 4 is cross-sectional view of the elongated shaft if FIG. 1 takenthrough a plane that extends through an interface between the elongatedshaft and a rotation knob, facing a proximal end of the jaw members;

FIG. 5 is a proximally-facing perspective view of a rotation knobdepicting a cavity for receiving an the elongated shaft of FIG. 1;

FIG. 6 is a cross-sectional, perspective view of the rotation knob ofFIG. 5 assembled to an outer shaft member of the elongated shaft of FIG.1;

FIG. 7 is a distally-facing perspective view of the rotation knob ofFIG. 5 depicting a groove for receiving a portion of the housing of FIG.1;

FIG. 8 is a perspective view of the rotation knob of FIG. 5 assembled tothe housing of FIG. 1;

FIG. 9 is a cross-sectional, perspective view of the end effectorassembled with the elongated shaft of FIG. 1;

FIG. 10 is a partial, perspective view of a distal portion of a jawactuation mechanism of the end effector of FIG. 1;

FIG. 11 is a partial, perspective view of distal portion of a knifeactuation mechanism of the end effector of FIG. 1;

FIG. 12 is a perspective view of a lower jaw member of the end effectorof FIG. 1 depicting a double flange at a proximal end thereof;

FIG. 13 cross-sectional, perspective view of the lower jaw member ofFIG. 12;

FIG. 14 is a schematic view of the nestled arrangement of the doubleflange of FIG. 12 with a double flange of an upper jaw member;

FIG. 15 is a schematic view of an alternative offset arrangement ofdouble flanges of an alternate pair of jaw members;

FIG. 16 is a partial, perspective view of an alternate embodiment of ajaw actuation mechanism depicting an alternate pair of jaw members witha nestled arrangement of double flanges coupled to an reciprocatingactuation rod by stamped links;

FIG. 17 is a perspective view of a proximal portion of the instrument ofFIG. 1 with a portion of the housing removed revealing internalcomponents;

FIG. 18 is a partial, side view of a proximal portion of the jawactuation mechanism of FIG. 10 depicting a connection between the handleand the jaw drive rod mechanism for imparting longitudinal movement tothe jaw drive rod;

FIG. 19 is a perspective view of a proximal portion of the knifeactuation mechanism of FIG. 11; and

FIG. 20 is a cross-sectional, perspective view of the knife actuationmechanism of FIG. 19.

FIG. 21A is a side view of the proximal portion of the instrument ofFIG. 17 depicting a movable handle in a separated position with respectto a stationary handle, which corresponds to the open configuration ofthe end effector depicted in FIG. 2A, and a knife trigger in a separatedconfiguration with respect to the stationary handle, which correspondsto an un-actuated or proximal configuration of a knife with respect tothe jaw members;

FIG. 21B is a side view of the proximal portion of the instrument ofFIG. 17 depicting the movable handle in an intermediate position withrespect to the stationary handle, which corresponds to a first closedconfiguration of the end effector wherein the jaw members encounter oneanother;

FIG. 21C is a side view of the proximal portion of the instrument ofFIG. 17 depicting the movable handle in an approximated configurationwith respect to the stationary handle, which corresponds to a secondclosed configuration of the end effector wherein the jaw members applyan appropriate pressure to generate a tissue seal;

FIG. 21D is a side view of the proximal portion of the instrument ofFIG. 17 depicting the knife trigger in an actuated configuration, whichcorresponds to an actuated or distal position of the knife with respectto the jaw members;

FIG. 22 is a perspective view of an alternate embodiment of an endeffector including upper and lower jaw members with scalloped distalends;

FIG. 23 is a cross-sectional, perspective view of an alternateembodiment of the lower jaw member of the end effector of FIG. 22;

FIG. 24 is a perspective view of the end effector of FIG. 22 coupled toan outer shaft member, illustrating a wire guide incorporated into aproximal portion of the upper and lower jaw members;

FIG. 25 is an exploded perspective view of an alternate embodiment of arotation knob constructed of two distinct components;

FIG. 26 is a perspective view of an alternate embodiment of an outershaft member for connection with the rotation knob of FIG. 25;

FIG. 27 is a cross-sectional, perspective view of the rotation knob ofFIG. 25 assembled to the outer shaft member of FIG. 26;

FIG. 28 is cross sectional, perspective view the rotation knob of FIG.25 coupled to a alternate embodiment of a housing, illustrating stopfeatures and detent arms for defining a “jaws up” configuration inaddition to a jaws right and jaws left configuration; and

FIG. 29 is an alternate embodiment of a jaw drive mechanism includingsingle-component a knife arm configured for connection to the knife ofFIG. 3 without additional fasteners.

DETAILED DESCRIPTION

The present disclosure relates to an electrosurgical apparatus andmethods for performing electrosurgical procedures. More particularly,the present disclosure relates to electrosurgically sealing tissue. Asis traditional, the term “distal” refers herein to an end of theapparatus that is farther from an operator, and the term “proximal”refers herein to the end of the forceps 10 which is closer to theoperator.

Referring initially to FIG. 1, an embodiment of an electrosurgicalforceps 10 generally includes a housing 12 that supports variousactuators thereon for remotely controlling an end effector 14 through anelongated shaft 16. Although this configuration is typically associatedwith instruments for use in laparoscopic or endoscopic surgicalprocedures, various aspects of the present disclosure may be practicedwith traditional open instruments and in connection with endoluminalprocedures as well.

The housing 12 is constructed of a left housing half 12 a and a righthousing half 12 b. The left and right designation of the housing halves12 a, 12 b refer to the respective directions as perceived by anoperator using the forceps 10. The housing halves 12 a, 12 b may beconstructed of sturdy plastic, and may be joined to one another byadhesives, ultrasonic welding or other suitable assembly methods.

To mechanically control the end effector 14, the housing 12 supports astationary handle 20, a movable handle 22, a trigger 26 and rotationknob 28. The movable handle 22 is operable to move the end effector 14between an open configuration (FIG. 2A) wherein a pair of opposed jawmembers 30, 32 are disposed in spaced relation relative to one another,and a closed or clamping configuration (FIG. 2B) wherein the jaw members30, 32 are closer together. Approximation of the movable handle 22 withthe stationary handle 20 serves to move the end effector 14 to theclosed configuration and separation of the movable handle 22 from thestationary handle 20 serves to move the end effector 14 openconfiguration. The trigger 26 is operable to extend and retract a knifeblade 56 (see FIG. 2A) through the end effector 14 when the end effector14 is in the closed configuration. The rotation knob 28 serves to rotatethe elongated shaft 16 and the end effector 14 about a longitudinal axisA-A extending through the forceps.

To electrically control the end effector 14, the housing 12 supports aswitch 36 thereon, which is operable by the user to initiate andterminate the delivery of electrosurgical energy to the end effector 14.The switch 36 is in electrical communication with a source ofelectrosurgical energy such as electrosurgical generator 40. Thegenerator 40 may include devices such as the LIGASURE® Vessel SealingGenerator and the Force Triad® Generator as sold by Covidien. A cable 42extends between the housing 12 and the generator 40 and may include aconnector (not shown) thereon such that the forceps 10 may beselectively coupled and decoupled electrically from the generator 40. Inother embodiments (not shown) a battery powered instrument may beprovided in which a generator and connector may be internal or integralto the instrument.

Referring now to FIGS. 2A and 2B, the end effector 14 may be moved fromthe open configuration (FIG. 2A) wherein tissue (not shown) may bereceived between the jaw members 30, 32, and the closed configuration(FIG. 2B), wherein the tissue may be clamped and sealed. Upper jawmember 30 and lower jaw member 32 are mechanically coupled to theelongated shaft 16 about a pivot pin 44. The upper jaw member 30 iselectrically coupled to cable 42, and thus to the generator 40, (seeFIG. 1) through a wire 46 b extending through the elongated shaft 16.The lower jaw member 32 is also coupled to the generator 40 by anotherwire 46 a (FIG. 4) extending through the elongated shaft 16. The wires46 a, 46 b provide an electrical pathway to a pair of electricallyconductive, tissue-engaging sealing plates 48, 50 disposed on the lowerand upper jaw members 32, 30, respectively. The sealing plate 48 of thelower jaw member 32 opposes a sealing plate 50 of the upper jaw member30, and, in some embodiments, the sealing plates 48 and 50 areelectrically coupled to opposite terminals, e.g., positive or active (+)and negative or return (−) terminals associated with the generator 40.Thus, bipolar energy may be provided through the end effector 14.Alternatively, the end effector 14 may be configured for deliveringmonopolar energy to the tissue. In a monopolar configuration, the endeffector 14 delivers electrosurgical energy from an active terminal,e.g. (+), while a return pad (not shown) is placed generally on apatient and provides a return path to the opposite terminal, e.g. (−),of the generator 40.

The jaw members 30, 32 may be pivoted about the pivot pin 44 to move theend effector 14 to the closed configuration of FIG. 2B wherein thesealing plates 48, 50 provide a pressure to the tissue graspedtherebetween. In some embodiments, to provide an effective seal, apressure within a range between about 3 kg/cm2 to about 16 kg/cm2 and,desirably, within a working range of 7 kg/cm2 to 13 kg/cm2 may beapplied to the tissue. Also, in the closed configuration, a separationor gap distance “G” may be maintained between the sealing plates 48, 50by an array of stop members 54 disposed on or adjacent the sealingplates 48, 50. The stop members 54 contact opposing surfaces on theopposing jaw member 30, 32 and prohibit further approximation of thesealing plates 48, 50. In some embodiments, to provide an effectivetissue seal, an appropriate gap distance of about 0.001 inches to about0.006 inches and, desirably, between about 0.002 and about 0.005 inchesmay be provided. In some embodiments, the stop members 54 areconstructed of an electrically non-conductive plastic or other materialmolded onto the jaw members 30, 32, e.g., by a process such asovermolding or injection molding. In other embodiments, the stop members54 are constructed of a heat-resistant ceramic deposited onto the jawmembers 30, 32. Other methods of controlling gap are contemplatedincluding those described in commonly assigned patent application Ser.No. 13/835,004 filed Mar. 15, 2013 entitled “Gap Control Via OvermoldTeeth and Hard Stops” (now U.S. Pat. No. 8,939,975).

Electrosurgical energy may be delivered to the tissue through theelectrically conductive seal plates 48, 50 to effect a tissue seal. Oncea tissue seal is established, a knife blade 56 may be advanced through aknife channel 58 defined in the jaw members 30, 32 to transect thesealed tissue. Knife blade 56 is depicted in FIG. 2A as extending fromthe elongated shaft 16 when the end effector 14 is in an openconfiguration. In some embodiments, a knife lockout is provided toprevent extension of the knife blade 56 into the knife channel 58 whenthe end effector 14 is in the open configuration, thus preventingaccidental or premature transection of tissue.

Referring now to FIG. 3, the elongated shaft 16 includes variouslongitudinal components that operatively couple the end effector 14 tothe various actuators supported by the housing 12 (FIG. 1). An outershaft member 60 defines an exterior surface of the elongated shaft 16and supports movement of other components therethrough as describedbelow. The outer shaft member 60 may be constructed from a flat stockpiece of metal. In constructing the outer shaft member 60, a stamping,punching or similar metal-working process may be employed to initiallygenerate a flat blank that includes an appropriate outer profile and anyinterior openings or features. Thereafter, the necessary folds, bendsand curves, etc., may be formed by bending the flat blank with a pressbrake, or other suitable metal-working equipment. In some instances,folds, bends and curves may be formed in metal components simultaneouslywith the outer profile and interior openings, or with the same equipmentemployed for forming the outer profile and interior openings. Thus, areference to a stamping process may be understood to include theformation of a flat profile, as well as imparting any curves, rolls orbends, etc., to the relevant component. The outer shaft member 60 may beformed by folding the flat blank into a generally rectangular profilesuch that two opposing longitudinal edges of the flat blank meet at alongitudinal seam 62 (see FIG. 4). The longitudinal seam 62 may bejoined by laser welding (or other suitable processes) the two opposinglongitudinal edges together to form a continuous rectangular profile.The seam 62 may be generally straight as depicted, or alternatively, abox joint, a dovetail joint or other interfaces known in themetal-working arts may be defined along the seam 62.

The outer shaft member 60 defines a clevis 64 at a distal end thereoffor receiving the jaw members 30 and 32. Opposing vertical sidewalls 64a and 64 b of the outer shaft member 60 extend distally of horizontalwalls 64 c and 64 d and include respective bores 66 a, 66 b extendingtherethrough. The bores 66 a, 66 b frictionally support the pivot pin 44and maintain an orientation of the pivot pin 44 with respect to theouter shaft member 60. Alternatively or additionally, the pivot pin 44may be fastened to the outer shaft member 60 by laser or heat-basedwelding, adhesives, chemical bonding, or other suitable processes.

At a proximal end of the outer shaft member 60, a pair of tabs 66 c(only one visible in FIG. 3) are provided to couple the outer shaftmember 60 to the rotation knob 28. The connection established betweenthe outer shaft member 60 and the rotation knob is described below withreference to FIGS. 5 and 6.

The pivot pin 44 extends through a proximal portion of each of the jawmembers 30, 32 to pivotally support the jaw members 30, 32 at the distalend of the outer shaft member 60. As described in greater detail belowwith reference to FIG. 12, a proximal portion of each of the jaw members30, 32 is configured as a “double flag” (alternately referred to as a“double flange”). The double flag configuration refers to the twolaterally spaced parallel flanges or “flags” 30 a, 30 b and 32 a, 32 brespectively, extending proximally from a distal portion of the jawmembers 30 and 32. A lateral cam slot 30 c and a lateral pivot bore 30 dextend through each of the flags 30 a, 30 b of the upper jaw member 30.Similarly, a lateral cam slot 32 c and a lateral pivot bore 32 d extendthrough each of the flags 32 a, 32 b of the lower jaw member 32. Thepivot bores 30 d, 32 d receive the pivot pin 44 in a slip-fit relationthat permits the jaw members 30, 32 to pivot about the pivot pin 44 tomove the end effector 14 between the open and closed configurations(FIGS. 2A and 2B respectively).

A distal portion of each of the jaw members 30, 32 extends distally ofthe outer shaft member 60. The distal portion of each of the jaw members30, 32 may be curved to facilitate manipulation of tissue and to providebetter “line of sight” for accessing organs and large tissue structures.As depicted in FIG. 3, the jaw members 30, 32 curve to the left from theperspective of a user. As described in greater detail below withreference to FIG. 8, for example, the end effector 14 may be rotatedabout the longitudinal axis A-A such that the jaw members 30, 32 curveto the right. In some alternative embodiments, as described below withreference to FIG. 28, for example, and end effector 220 may be rotatedto a stable orientation where jaw members 222, 224 curve in an upwarddirection.

A pair of wire guides 68 are provided to protect the wires 46 a, 46 b(FIG. 4) The wire guides 68 are positioned adjacent interior surfaces ofthe opposing vertical sidewalls 64 a and 64 b of the outer shaft member60. Adhesives, screws or similar fastening mechanisms may be employed toaffix the wire guides 68 such that position of the wire guides 68 may bemaintained. In some alternative embodiments, as described below withreference to FIG. 23, wire guides 68 may be eliminated and structuresmay be incorporated into nearby components which may serve as wireguides.

The wire guides 68 are generally flat and may be constructed of metal, alubricious plastic such as polytetrafluoroethylene (PTFE) or similarmaterial. The wire guides 68 may thus provide a bearing surface for theexterior surfaces of flags 32 a and 32 b of the lower jaw member 32 asthe jaw members 30, 32 pivot about the pivot pin 44. The wire guides 68include a longitudinal passageway 70 through which a respective one ofthe wires 46 a, 46 b (FIG. 4) may extend to connect the sealing plates48, 50 (FIG. 2A) to the electrosurgical generator 40 (FIG. 1). Thepassageways 70 maintain the wires against the sidewalls 64 a, 64 b ofthe clevis 64 to discourage entanglement of the wires due to motion ofthe various components within the elongated shaft 16. A distal flare 72is provided in the passageways 70 to provide clearance for the wires tomove with the jaw members 30, 32 as the jaw members 30, 32 pivot. Holes74 are provided in the wire guides 68 to permit passage of the pivot pin44 therethrough, and slots 76 are provided to guide motion of a cam pin92 as described below with continued reference to FIG. 3. The slots 76are optional and may be excluded from the wire guides 68 in somealternative embodiments where the cam pin 92 is sufficiently short. Theholes 74 and the slots 76 are disposed on a central axis of the wireguides 68, and thus, two identical wire guides 68, oriented oppositely,may provide proper alignment with the holes 66 a and 66 b on outer shaftmember 60.

A pair of wire conduits 78 a and 78 b may be provided to guide wires 46a and 46 b (FIG. 4) proximally of the wire guides 68. The wire conduits78 a, 78 b may be constructed of a plastic tube, and serve to protectthe wires 46 a, 46 b from sharp edges that may form on surroundingcomponents. The wire conduits 78 a, 78 b may also provides some rigidityto facilitate feeding the wires 46 a, 46 b into position duringassembly.

A jaw drive rod 80 is received within the outer shaft member 60 and isconfigured for longitudinal motion with respect to the outer shaftmember 60. The jaw drive rod 80 is constructed from a flat, metal stockpiece, and may be formed by a stamping process similar to the formationof the outer shaft member 60 as described above. The jaw drive rod 80generally exhibits a U-shaped profile including sidewalls 82 a, 82 b anda u-shaped connector portion 82 c. Horizontal flanges 84 a and 84 bprotrude laterally from the respective sidewalls 82 b and 82 a andlaterally support the jaw drive rod within the outer shaft member 60. Adistal portion 86 of the jaw drive rod 80 is configured for receiptwithin the outer shaft member 60 and includes features for operativelycoupling the jaw drive rod 80 to the end effector 14. A proximal portion88 of the jaw drive rod 80 is configured for receipt within the housing12 (FIG. 1), and includes features for operatively coupling the jawdrive rod 80 to the actuators supported thereon, e.g. the movable handle22.

The distal portion 86 of the jaw drive rod 80 includes a round hole 90extending through the sidewalls 82 a, 82 b for receiving the cam pin 92.The cam pin 92 may be friction fit, welded or otherwise fastened withinthe hole 90 such that the cam pin 92 is fixedly coupled to the jaw driverod 80 and protrudes laterally from each of the sidewalls 82 a and 82 b.Distally of the hole 90, a longitudinal slot 96 is defined through thesidewalls 82 a, 82 b. The longitudinal slot 96 provides clearance forthe pivot pin 44, and thus, permits longitudinal reciprocation of thejaw drive rod 80 independent of the pivot pin 44.

An overfold 98 is defined in the vicinity of the hole 90 and the slot96. A portion of the sidewall 82 b is folded toward the opposingsidewall 82 a such that a portion of the jaw drive rod 80 exhibits agenerally closed profile in the vicinity of the overfold 98. Asdescribed in greater detail below with reference to FIG. 4, the overfold98 permits the jaw drive rod 80 to serve as a knife guide to guide themotion of a knife 102.

The proximal portion 88 of the jaw drive rod 80 includes a set oflaterally protruding collar stops 88 a, 88 b and 88 c, and a pair oflaterally protruding spring stops 88 d, 88 e. The collar stops 88 a, 88b, 88 c engage a drive collar 184, and the spring stops 88 d, 88 eengage a spring keeper 192, which, as described below with reference toFIG. 18, cooperate to operatively couple the jaw drive shaft 80 to themovable handle 22.

The knife 102 is a generally flat, metal component defining a profilethat may be constructed by a stamping process as described above. Theknife 102 supports the sharpened knife blade 56 at a distal-most endthereof. The sharp edge of the knife blade 56 may be applied to thedistal end of the knife 102 subsequent to the stamping process thatforms the profile. For example, various manufacturing techniques may beemployed such as grinding, coining, electrochemical etching or othersuitable manufacturing processes for forming sharpened edges. Alongitudinal slot 106 is defined with the knife 102 to provide clearancefor the pivot pin 44 and the cam pin 92. Proximal tabs 108 a, 108 bprotrude from the knife 102 and provide a mechanism for operativelycoupling the knife 102 to the trigger 26. The connection between theknife 102 and the trigger 26 is described in detail below with referenceto FIGS. 19 and 20.

Referring now to FIG. 4, the various components of the elongated shaft16 are depicted assembled to one another and to the upper and lower jawmembers 30, 32. The outer shaft member 60 is secured to the rotationknob 28 by the engagement of the tabs 66 c on the outer shaft member 60with the rotation knob 28 (see also, FIG. 6). The jaw drive rod 80 ispositioned within the outer shaft member 60 such that the horizontalflanges 84 a and 84 b of the jaw drive rod 80 abut the sidewalls 64 aand 64 b of the outer shaft member 60. The wire guides 68 are positionedbetween the sidewalls 64 a and 64 b of the outer shaft member 60 and theflags 32 a, 32 b of the lower jaw member 32, thus, providing lateralsupport to the lower jaw member 32. The flags 30 a, 30 b of the upperjaw member 30 are disposed laterally within the flags 32 a, 32 b of theof the lower jaw member 32. This arrangement of flags 30 a, 30 blaterally within the flags 32 a, 32 b may be described as a “nestled”arrangement. Other arrangements are contemplated such as the “offset”arrangement described below with reference to FIG. 15.

The knife 102 is centrally disposed within the jaw drive shaft 80. Thesidewalls 82 a, 82 b of the jaw drive shaft 80 provide lateral supportto the knife 102, and vertical support is provided by the u-shapedconnector portion 82 c and the over-fold 98. The knife 102 issubstantially surrounded at its distal end by the jaw drive shaft 80 onfour lateral sides, and by substantially surrounding the knife 102 atits distal end, the jaw drive shaft 80 constrains the motion of theknife 102 in the four lateral directions. Free motion of the knife 102is permitted only in a longitudinal direction. Thus, the jaw drive shaft80 serves as a knife guide by urging the knife 102 into a centralposition within the elongated shaft 16, and thus ensuring properalignment of the knife 102 as the knife 102 reciprocates within knifechannel 58 (FIG. 2A). By substantially surrounding the knife 102 at itsdistal end, the jaw drive rod 80 restricts movement of the knife 102 intwo orthogonal lateral planes, e.g. a vertical and a horizontal plane.The jaw drive rod 80 may also serve to protect the knife 102 and othercomponents from damage throughout the assembly of the elongated shaft 16and jaw members 30, 32.

Referring now to FIGS. 5 and 6, the rotation knob 28 is configured as asingle component. In some alternative embodiments, as described belowwith reference to FIG. 25, for example, a rotation knob 260 may beprovided that is constructed of multiple components affixed to oneanother. The rotation knob 28 includes a distal opening 112 definedtherein for receiving the outer shaft member 60. The distal opening 112is bounded by lateral walls 112 a, 112 b, 112 c and 112 d, which definea generally rectangular profile corresponding to the rectangular profileof the outer shaft member 60. The distal opening 112 includes aninterior landing 114 for seating a proximal-most surface of the outershaft member 60 and two lateral latch pockets 116 for receiving the tabs66 c of the outer shaft member 60. The tabs 66 c are flexible andproject laterally outward in a distal direction such that the insertionof the proximal end of the outer shaft member 60 onto the distal opening112 of the rotation knob 28 induces the tabs to flex inwardlymomentarily as the tabs 66 c engage lateral walls 112 a, 112 b, and thenreturn to the outwardly projecting orientation inside the latch pockets116. The tabs 66 c thus lock the outer shaft member 60 to the rotationknob 28. Due to the rectangular profile of the outer shaft member 60 andthe opening 112, rotational motion imparted to the rotation knob 28about the longitudinal axis A-A (FIG. 1) is transferred to the outershaft member 60.

A passageway 120 is defined through the rotation knob 28 to permitlongitudinal motion of the jaw drive shaft 80 (FIG. 3) therethrough. Thepassageway 120 is shaped such that rotational motion imparted to therotation knob 28 is transferred to the jaw drive shaft 80. In oneembodiment, a cable clearance passageway 122 is also defined throughrotation knob 28 to permit passage of electrical cables (e.g., 46 a, 46b, FIG. 4) that electrically couple the sealing plates 48, 50 (FIG. 2A)to the electrosurgical generator 40 (FIG. 1). Rotational motion impartedto the rotation knob 28 may thus impart rotational motion to each of thecomponents of the elongated shaft 16, and to the end effector 14, whichis coupled thereto.

Referring now to FIGS. 7 and 8, a proximal end of the rotation knob 28is configured to engage the housing 12. A circular groove 124 is definedaround a circular boss 126 projecting proximally from the rotation knob28. The circular groove 124 receives an inwardly projecting wall (notvisible) of the housing 12 to maintain the rotation knob 28 against thedistal end of the housing 12. The circular groove 124 guides therotational motion of the rotation knob 28 about the longitudinal axisA-A (FIG. 1).

The rotational motion of the rotation knob 28 may be limited by a stopboss 130 projecting distally from the housing 12. The stop boss 130 ispositioned to engage rotation stops 134 on the rotation knob 28 toprevent rotational motion of the rotation knob further than, forexample, 180 degrees in either direction. Detents 136 project proximallyfrom the rotation knob 28 to engage a distal surface of the stop boss130 prior to the stop boss 130 engaging the rotation stops. When therotation knob 28 is rotated to a position wherein the stop boss 130 ispositioned between a rotation stop 134 and a detent 136, the rotationalposition of the rotation knob 28 is relatively stable, and may bereleasably maintained until a sufficient force is supplied to move thedetents 136 over the stop boss 130. Two radially opposite positions aredefined wherein the rotational position of the rotation knob 28 isrelatively stable. These two radially opposite positions correspond withtwo orientations of the end effector 14 (FIG. 1) in which the jawmembers 30, 32 curve to the right and to the left from the perspectiveof a user.

Referring now to FIG. 9, the end effector 14 is coupled to the distalend of the elongated shaft 16 by the pivot pin 44. The pivot pin 44 iscoupled to the sidewalls 64 a and 64 b of the clevis 64 defined at thedistal end of the outer shaft member 60. Thus, the pivot pin 44represents a longitudinally stationary reference for the longitudinalmovements of jaw drive rod 80 and the knife 102. Laterally inward of thesidewalls 64 a, 64 b, the pivot pin 44 extends through the wire guides68, the flags 32 a, 32 b of the lower jaw member 32, the flags 30 a and30 b of the upper jaw member 30, the sidewalls 82 a, 82 b of the jawdrive shaft 80, and the knife 102. The jaw members 30, 32 are free topivot about the pivot pin 44, and the jaw actuation shaft 80 and theknife 102 are free to translate longitudinally around the pivot pin 44.

Referring now to FIG. 10, the jaw drive rod is 80 is disposed in adistal position maintaining the end effector 14 in the openconfiguration. Since the jaw drive rod 80 is coupled to the cam pin 92,when the jaw drive rod 80 is in the distal position, the cam pin 92 islocated in a distal position in cam slots 30 c and 32 c defined throughthe flags 30 a, 30 b, 23 a, 32 b of the jaw members 30, 32. Also, whenthe jaw drive rod 80 is in the distal position, a distal-most face 86 aof the jaw drive rod 80 extends to a tissue receiving region 14 a of theend effector 14. Thus, the jaw drive rod 80 provides a stop to preventthe entry of tissue into the elongated shaft 16.

The jaw drive rod 80 may be drawn proximally relative to the pivot pin44 (the stationary longitudinal reference) to move the end effector 14to the closed configuration (see FIG. 2B). Since the longitudinalposition of the pivot pin 44 is fixed (by the outer shaft member 60,which is removed from view in FIG. 10 for clarity), and since the camslots 30 c, 32 c are obliquely arranged with respect to the longitudinalaxis A-A, proximal retraction of the cam pin 92 through the cam slots 30c, 32 c induces the jaw members 30, 32 to pivot toward one another aboutthe pivot pin 44. Conversely, when the end effector 14 is in the closedconfiguration, longitudinal translation of the jaw drive rod 80 in adistal direction induces the jaw members 30, 32 to pivot away from oneanother toward the open configuration.

Referring now to FIG. 11, when the end effector 14 is in the closedconfiguration, the knife 102 is freely movable in a longitudinaldirection within the jaw drive shaft 80. The slot 106 in the knife 102extends around the both the pivot pin 44 and the cam pin 92, and thusthe pins 44, 92 do not interfere with the reciprocal motion of the knife102. The blade 56 at the distal-most end of the knife 102 is centrallyaligned by the distal-most end of the jaw drive rod 80 that includes thefold-over 98. Properly aligned, the blade 104 readily enters the knifechannel 58 defined in the jaw members 30, 32. The portion of the knife102 extending distally from the jaw drive rod 80 is free to bend and,thus, the blade 104 follows the curvature of the knife channel 58through the jaw members 30, 32 as the knife 102 reciprocateslongitudinally.

Referring now to FIGS. 12 and 13, the lower jaw member 32 is constructedof three major components. These components include a double-flag jawinsert 140, an insulator 142 and the sealing plate 48. In somealternative embodiments, as described below with reference to FIG. 22,for example, a jaw member 224 may be provided that is constructed ofmajor components arranged to provide unique advantages.

The flags 32 a, 32 b of the jaw member 32 define a proximal portion ofthe double-flag jaw insert 140, and a generally u-shaped channel 144extends distally to support the tissue engaging portion of the jawmember 32. The double-flag jaw insert 140 includes various planarsurfaces, and may be constructed as a sheet metal component formed by astamping process as described above. In such a stamping process, the camslots 32 c and pivot holes 32 d may be punched into a flat blank, andsubsequently the blank may be bent to form the flags 32 a, 32 b and theu-shaped channel 144. A lateral bend may also be applied to the jawinsert 140 to accommodate the curvature of the jaw member 32.

The insulator 142 may be constructed of an electrically isolativeplastic such as a polycarbonate (PC), acrylonitrile butadiene styrene(ABS), or a blend (PC/ABS) thereof. The electrically isolative plasticmay be overmolded onto the jaw insert 140 in a single-shot injectionmolding process. Various features may be molded into the insulator 142that facilitate the attachment of the sealing plate 48 to the insert140. For example, tabs may be provided that permit a snap-fit attachmentof the sealing plate 48, or ridges may formed that permit ultrasonicwelding of the sealing plate onto the insulator 142. The sealing plate50 may be constructed of an electrically conductive metal, and may bestamped from a flat sheet stock.

Referring now to FIG. 14, the flags 30 a, 30 b of the upper jaw member30 are depicted schematically in a nestled configuration with respect tothe flags 32 a, 32 b of the lower jaw member 32. A. The proximal portionof the upper jaw member 30 is narrower than the proximal portion of thelower jaw member 32, and thus, a lateral spacing “S” between the flags32 a, 32 b is sufficient to permit the flags 30 a and 30 b to bepositioned therebetween. A pivot axis “P0” extends through anoverlapping portion of the flags 30 a, 32 a, and 30 b, 32 a such thatthe upper and lower jaw members 30, 32 may pivot about the common axis“P0.” In the nestled configuration, the proximal portions of the upperand lower jaw members 30, 32 also share a common centerline “CL−1” thatis transverse with respect to the pivot axis “P0.”

An alternative to the nestled configuration illustrated in FIG. 14 isthe offset configuration illustrated schematically in FIG. 15. Aproximal portion of double-flag upper jaw member 150 includes flags 150a and 150 b. A proximal portion of a double-flag lower jaw member 152includes flags 152 a and 152 b and exhibits a width that is identical toa width of the proximal portion of the upper jaw member 150. To providean overlapping portion of the flags 150 a, 152 a and 150 b, 152 b suchthat the jaw members 150, 152 may pivot about the common axis “P0,” oneflag 150 a of the upper jaw member 150 is positioned on a laterallyexterior side of the corresponding flag 152 a of the lower jaw member152, and the other flag 150 b of the upper jaw member 150 is positionedon a laterally interior side of the corresponding flag 152 b of thelower jaw member 152. In the offset configuration, a centerline “CL−2”of the proximal portion of the upper jaw member 150 is laterally offsetwith respect to a centerline “CL−3” of the lower jaw member 152.

In embodiments where a distal, tissue engaging portion (depicted inphantom) of the jaw members 150, 152 is generally straight, e.g.,without the lateral curve of jaw members 30, 32 (see, e.g., FIG. 2B),the offset configuration permits the jaws 150 and 152 to be constructedas substantially identical components. The straight distal portions ofthe jaw members 150, 152 may be aligned along a common centerline “CL−4”although proximal portions of the jaw members 150, 152 are aligned alongtheir respective centerlines “CL−2” and “CL−3.” Generally, a forcepswith identically configured jaw members 150, 152 may be relativelyeconomical to produce.

Referring now to FIG. 16, an alternate embodiment of an actuationmechanism 160 is depicted. The actuation mechanism 160 employs a pair ofstamped lever links 162, 164 for opening and closing a pair of jawmembers 166, 168. An upper jaw member 166 includes a proximal flange 166a pivotally coupled to a lower lever link 162 about pivot axis “P1.” Alower jaw member 168 includes proximal flanges 168 a pivotally coupledto an upper lever link 164 about pivot axis “P2.” Each of the proximalflanges 166 a and 168 a may also be constructed as stamped metalcomponents as described above. The lever links 162, 164 are pivotallycoupled to a reciprocating drive rod 170 about respective pivot axes“P3” and “P4” and each of the proximal flanges 166 a, 168 a is pivotallycoupled about a pivot pin 172, which is arranged about a pivot axis“P5.” The pivot pin 172 is coupled to an outer shaft member (not shown),and thus represents a fixed reference for the motion of the motion ofthe actuation mechanism 160.

The reciprocating drive rod 170 is movable in a distal longitudinaldirection as indicated by arrow “D1” and a proximal longitudinaldirection, as indicated by arrow “D2.” Since the longitudinal positionof the pivot pin 172 is fixed, longitudinal movement of thereciprocating drive rod 170 induces the link 162 to pivot simultaneouslyabout axes “P1” and “P3,” and induces link 164 to pivot simultaneouslyabout axes “P2” and “P4.” This simultaneous pivoting of the links 162,164 induces the jaw members 166, 168 to pivot about the axis “P5”between the closed configuration depicted and an open configuration (notshown).

The double flag jaw members 166, 168 include proximal flanges 166 a, 168a arranged in a nestled configuration (see FIG. 14). The upper link 164may also be characterized as “nestled,” or disposed laterally between,the flags of proximal flange 168 a of the lower jaw member 168. Theproximal flange 166 a of the upper jaw member 166 is “nestled” withinthe lower lever link 162. Each of the pivot links 162, 164 and theproximal flanges 166 a, 168 a include a generally u-shaped cross sectionto permit the pivot links 162, 164 to interleave with the proximalflanges 166 a, 168 a in this manner. This configuration provides acentral channel 174 through which a knife or other centrally disposeddrive component (not shown) may extend.

The actuation mechanism 160 allows the jaw members 166, 168 to open orseparate from one another to a greater degree than an actuationmechanism for opening similarly sized jaw members employing a simple camslot (see, e.g., FIG. 10). The actuation mechanism 160 also provides atactile feel that some operators may prefer. The stamped lever links162, 164 and proximal flanges 166 a, 168 a provide a relatively strongactuation mechanism 160, which permits the jaw members 166, 168 to applya relatively large force to tissue captured therebetween.

Referring now to FIG. 17, the connection of the movable handle 22 andthe knife trigger 26 to the longitudinally movable components of theelongated shaft 16 is described. The movable handle 22 may bemanipulated to impart longitudinal motion to the jaw drive rod 80 (FIG.10), and knife trigger 26 may be manipulated to impart longitudinalmotion to the knife 102 (FIG. 11). As discussed above, longitudinalmotion of the jaw drive rod 80 serves to move the end effector 14between the open configuration of FIG. 2A and the closed configurationof FIG. 2B, and longitudinal motion of the knife 102 serves to moveknife blade 56 through knife channel 58 (FIG. 2A).

The movable handle 22 is operatively coupled to the jaw drive rod 80 bya connection mechanism 176. The connection mechanism 176 includes aclevis 178 defined at an upper end of the movable handle 22. The clevis178 is pivotally supported on the right housing half 12 a by a pivotboss 180. A second complementary pivot boss 180 (not shown) is providedon the left housing half 12 b (FIG. 1) to support the clevis 178. Eachof two upper flanges 178 a and 178 b of the clevis 178 include roundeddrive surfaces 182 a and 182 b thereon for engaging respective rims 184a and 184 b of a drive collar 184 (FIG. 18). The drive surfaces 182 a,182 b are arranged along the longitudinal axis A-A such that pivotalmotions of the movable handle 22 about the pivot bosses 180 inducecorresponding longitudinal motions of the drive collar 184 along thelongitudinal axis A-A.

Referring now to FIG. 18, a distal longitudinal motion may be impartedto the connection mechanism 176 by pushing the distal rim 184 a of thedrive collar 184 with the movable handle 22 (FIG. 17) as indicated byarrow D3. The distal rim 184 a engages the collar stops 88 a (FIG. 3),88 b and 88 c. Thus, the distal longitudinal motion of the drive collar184 will be transmitted directly to the jaw drive rod 80 to induce acorresponding distal motion of the jaw drive rod 80. A proximallongitudinal motion may be imparted to the connection mechanism 176 bypushing the proximal rim 184 b of the drive collar 184 with the movablehandle 22 (FIG. 17) as indicated by arrow D4. The proximal rim 184 bengages a compression spring 188, which is constrained between theproximal rim 184 b and a spring keeper 192. The spring keeper 192engages the spring stops 88 d (FIG. 3) and 88 e of the jaw drive rod 80.Thus, the proximal motion of the drive collar 184 is transmitted to thejaw drive rod 80 through the compression spring 188 and the springkeeper 192.

Proximal movement of the jaw drive rod 80 draws the cam pin 92proximally to pivot the jaw members 30, 32 toward one another to movethe end effector 14 to the closed configuration as described above withreference to FIG. 10. Once the jaw members 30 and 32 are closed, the jawdrive rod 80 essentially bottoms out (i.e., further proximal movement ofthe jaw drive rod 80 is prohibited since the jaw members 30, 32 contactone another). Further proximal movement of the movable handle 22 (FIG.17), however, will continue to move the drive collar 184 proximally.This continued proximal movement of the drive collar 184 compresses thespring 188. When compressed, the spring 188 imparts additional force tothe jaw drive rod 80, which results in additional closure force appliedto tissue captured between the jaw members 30, 32 (see FIG. 2B). Thespring 188 also serves to bias the jaw members 30, 32 and the movablehandle 22 to the open configuration.

A rotation spacer 196 is supported at the proximal end of the jaw driverod 80. The rotation spacer 196 includes an interior passageway (notshown) that receives the irregular cross-section of the jaw drive rod80. An outer surface of the rotation spacer 196 is generallycylindrical, and thus, the rotation spacer 196 may support the proximalend of the jaw drive rod 80 within the housing 12 (see FIG. 17) throughrotation of the elongated shaft 80 about the longitudinal axis A-A,e.g., rotation induced by rotation of the rotation knob 28 (FIG. 17). Insome embodiments, e.g., where longitudinal translation between therotation spacer 196 and spring keeper 192 is not required, the rotationspacer 196 and the spring keeper 192 may be constructed as a singlecomponent as depicted in phantom. The single component spring keeper 192and rotation spacer 196 may be coupled to the jaw drive shaft 80 by adowel pin (not shown).

Referring again to FIG. 17, the trigger 26 is pivotally supported in thehousing 12 about a pivot boss 202 protruding from the trigger 26. Thetrigger 26 is operatively coupled to the knife 102 (FIG. 11) by a knifeconnection mechanism 204 such that pivotal motion of the trigger 26induces longitudinal motion of the knife 102. The knife connectionmechanism 204 includes upper flanges 26 a, 26 b of the trigger 26, alink 208, and a knife carriage 210. The link 208 is pivotally coupled tothe flanges 26 a, 26 b and the knife carriage 210 such that pivotalmotion of the trigger 26 induces longitudinal motion of the knifecarriage 210.

Referring now to FIG. 19, the knife carriage 210 is longitudinallymovable over the jaw drive rod 80 independently of the motion of the jawdrive rod 80. Thus, the jaw drive rod 80 may be regarded as a stationaryreference for the movement of the knife carriage 210. The knife carriage210 includes a sleeve 212, a knife arm 216, and a cap 218.

The knife arm 216 includes a pivot boss 216 a, about which the link 208(see FIG. 21C) is coupled to knife arm 216. As described below withreference to FIG. 21C, the link 208 imparts longitudinal movement to theknife carriage 210 in a distal direction of arrow A9. Guide arms 216 bprotrude laterally from the proximal end of the knife arm 216, andengage a respective guide slot 12 c (shown schematically in FIG. 19 andvisible in FIG. 21C) defined in the housing 12 to guide the longitudinalmotion of the knife carriage 210.

The sleeve 212 is coupled to the knife arm 216, and thus, the sleeve 212translates along with the knife bar 216. The sleeve 212 includesindentations or catches 212 a defined therein, which receive snap-inarms 218 a of the cap 218. The cap 218 may thus be assembled to thesleeve 212 such that cap 218 and the sleeve 212 translate together.Thus, the entire knife carriage 210, i.e., the knife bar 216, the sleeve212 and the cap 218, may all be induced to translate together along thejaw drive rod 80 in the direction of arrow A9. The knife carriage 210abuts a spring 219, which is compressed against the rotation knob 28(shown schematically in FIG. 19) when the knife carriage 210 translatesin the direction of arrow A9. The spring 219 biases the knife carriage210 in a proximal direction to a proximal position along the jaw driverod 80.

Referring now to FIG. 20, the knife 102 is coupled to the knife carriage210 such that the longitudinal motion of the knife carriage 210 istransmitted to the knife 102. The proximal tabs 108 a, 108 b protrudingfrom the knife 102 are captured between the sleeve 212 and the cap 218,and thus the knife 102 will translate with the knife carriage 210 inboth the proximal and distal directions. The proximal tabs 108 a, 108 bare free to rotate about the longitudinal axis A-A within the sleeve212, and thus, the knife 102 may rotate along with the jaw drive rod 80within the knife carriage 210 when the rotation knob 28 is rotated asdescribed above.

Referring now to FIGS. 21A, 21B, 21C and 21D, a sequence of motions maybe initiated by moving the movable handle 22 to induce motion in the jawdrive mechanism in order to close the jaws 30, 32, and by moving thetrigger 26 to induce motion in the knife actuation mechanism in order totranslate the bade 56 through the jaws 30, 32. Initially, both themoveable handle 22 and the knife trigger 26 are in a distal orun-actuated position as depicted in FIG. 21A. This arrangement of themoveable handle 22 and trigger 26 sustains the end effector 14 in theopen configuration (FIG. 2A) wherein the jaw members 30, 32 aresubstantially spaced from one another, and the knife blade 56 is in aretracted or proximal position with respect to the jaw members 30, 32.The initial distal position of the trigger 22 is actively maintained bythe influence of the spring 219 on the knife actuation mechanism. Thedistal position of the moveable handle 22, however, is only passivelymaintained, e.g., by internal friction within the jaw actuationmechanism. When both the moveable handle 22 and the knife trigger 26 arein the distal, un-actuated position, pivotal motion of the knife trigger26 in a proximal direction, i.e., toward the stationary handle 20, isprohibited by interference between the trigger 26 and moveable handle22. This interference prohibits advancement of the knife blade throughthe jaw members 30, 32 when the end effector 14 is in the openconfiguration.

The movable handle 22 may be moved from the distal position of FIG. 21Ato the intermediate position depicted in 21B to move the jaw members 30,32 to the closed configuration (FIG. 2B). As the movable handle 22pivots about the pivot boss 180 in the direction of arrow M1, the drivesurface 182 b engages the proximal rim 184 b of the drive collar 184.The drive collar 184, the spring 188 and the spring keeper 192 are alldriven proximally against the spring stops 88 d and 88 e of the jawdrive rod 80, and thus, the jaw drive rod 80 is driven proximally in thedirection of arrow M2. As discussed above with reference to FIG. 10,proximal movement of the jaw drive rod 80 serves to draw the cam pin 92proximally though the cam slots 30 c, 32 c of the jaw members 30, 32 andthus pivot the jaw members 30, 32 toward one another. As the jaw members30, 32 engage one another and no further pivotal movement of the jawmembers 30, 32 may be achieved, the jaw actuation mechanism “bottomsout” and further proximal movement of the cam pin 92 and the jaw driverod 80 is prohibited.

The movable handle 22 may be moved from the intermediate position ofFIG. 21B to the actuated or proximal position of FIG. 21C to increasethe pressure applied by the jaw members. 30, 32. As the movable handle22 pivots further about the pivot boss 180 in the direction of arrow M3,the drive surface 182 b presses the proximal rim 184 b of the drivecollar 184 further distally against the spring 188 in the direction ofarrow M4. The spring 188 is compressed against the spring keeper 192,and a tensile force is transmitted through the jaw drive rod 80 to thejaw members 30, 32. The tensile force supplied by the spring 188 ensuresthat the jaw members 30, 32 apply an appropriate pressure to effect atissue seal. When the movable handle 22 is in the actuated or proximalposition, electrosurgical energy may be selectively supplied to the endeffector 14 to generate a tissue seal.

When the movable handle 22 is in the actuated or proximal position, aflange 22 a on the moveable handle 22 is received in a railway 20 asupported within the stationary handle 20. The railway 20 a serves totemporarily lock the movable handle 22 in the proximal position againstthe bias of the spring 188, which biases the movable handle 22 from theproximal position of FIG. 21C to the intermediate position of FIG. 21B.Thus, the railway 20 a permits the maintenance of pressure at the endeffector 14 without actively maintaining pressure on the movable handle22. The flange 22 a may be released from the railway 20 a by pivotingthe movable handle 22 proximally and releasing the movable handle 22 tomove under the influence of the spring 188. Operation of the railway 20a is described in greater detail in U.S. patent application Ser. No.11/595,194 to Hixon et al., now U.S. Pat. No. 7,766,910. In someembodiments (not shown), the flange 22 a and the railway 22 a may beeliminated to provide an instrument without the temporary lockingcapability provided by these features.

When the movable handle 22 is in the actuated or proximal position, theknife trigger 26 may be selectively moved from the distal position ofFIG. 21C to the proximal position of FIG. 21D to advance the knife blade56 distally through the jaw members 30, 32. The knife trigger 26 may bepivoted in the direction of arrow M5, about pivot boss 202 to advancethe flange 26 b of the knife trigger 26 distally in the direction ofarrow M6. Movement of the flange 26 b induces the link 208 to pivot withrespect to the flange 26 b of the trigger 26, and with respect to theknife arm 216 such that the link 208 draws the knife carriage 210distally in the direction of arrow M7. As described above with referenceto FIGS. 11 and 19-20, distal movement of the knife carriage 210advances the knife blade 56 distally through the jaw members 30, 32.

Referring now to FIGS. 22-29, various alternate components aredescribed, which may be substituted individually or in combination forthe similarly named components described above in order to providespecific functionality to a surgical instrument. With reference to FIG.22, an alternate embodiment of an end effector 220 includes upper andlower jaw members 222 and 224 respectively, which are configured tofacilitate blunt dissection of tissue. Each jaw member 222, 224 exhibitsa scalloped distal end with a ledge 222 a, 224 a protruding distallyfrom a less prominent portion 222 b, 224 b of the distal tip. When theend effector 220 is in the closed configuration as depicted, the ledges222 a, 224 a may be pressed into tissue to be dissected. The endeffector 220 may then be moved to the open configuration to separate thejaw members 222, 224 and any tissue gripped by the ledges 222 a, 224 a.

The ledges 222 a, 224 a may be constructed of an electrically isolativematerial, e.g., the insulator 230 as depicted in FIG. 23. The upper jawmember 222 is constructed of three major components including adouble-flag jaw insert 234, the insulator 230 and a sealing plate 238.The insulator 230 may molded onto a u-shaped channel 236 of the of thedouble-flag jaw insert 234 and the sealing plate 238 in a single-shotmolding operation. The insulator 230 may completely surround theu-shaped channel 236, and may include various features such as the ledge224 a (FIG. 22) at the distal end thereof, and a wire guide 240 at aproximal end thereof.

The wire guide 240 is a portion of the insulator 230 that is molded to alateral side of the double-flag jaw insert 234, and over the wire 46 bthat couples the sealing plate 238 to the electrosurgical generator 40(FIG. 1) as described above. The wire guide 240 includes a hole 244 toprovide clearance for a pivot pin 44 (FIG. 24), and is disposed on asingle lateral side of the upper jaw member 222. Lower jaw member 224(FIG. 22) may include a similar wire guide (not shown), which may bepositioned on the opposing lateral side when the upper and lower jawmembers 222, 224 are assembled to an outer shaft member 250 in an“offset” arrangement as depicted in FIG. 24. The wire guide 240 may thusprotect the wire 46 b from abrasion from the outer shaft member 250 asthe upper jaw member 222 pivots about pivot pin 44.

Referring now to FIG. 25, a rotation knob 260 is constructed of twodistinct components 262 and 264. An exterior component 262 providesgripping surfaces 268 which may be engaged by an operator in use. Theexterior component 262 generally exhibits a thin wall construction tofacilitate molding from a plastic or similar material. Inner wallportions 270 are provided to engage an inner component 264 of therotation knob 260 in a snap-fit manner. The inner component 264 includesa distal engagement portion 272 for coupling the rotation knob 260 tothe outer shaft member 250 (see FIG. 27), and a circular boss 276extending proximally therefrom. The circular boss 276 includes radiallyspaced detents 278 projecting radially from an outer circumferencethereof and a proximal extension 280 protruding longitudinallytherefrom. The detents 278 and proximal extension 280 define therotational limits of the rotation knob 260 as described below withreference to FIG. 28.

Referring now to FIGS. 26 and 27, the outer shaft member 250 may becoupled to the rotation knob 260 in a snap-fit manner. The outer shaftmember 250 includes a pair of rectangular openings 284 extending throughvertical sidewalls 250 a, 250 b near a proximal end thereof. Therectangular openings 284 provide flexibility to the proximal end of theouter shaft member 250 such that a pair of latches 288 at a proximal endof the sidewalls 250 a, 250 b may be installed into the distalengagement portion 272 of the interior component 264 of the rotationknob 260. The distal engagement portion 272 includes tapered walls 272a, 272 b to urge the latches 288 laterally inward temporarily as theouter shaft member 250 is inserted longitudinally between the walls 272a, 272 b. Once the latches 288 have been inserted proximally beyond thewalls 272 a, 272 b, the latches 288 will snap into place as theresiliency of the outer shaft member 250 urges the latches laterallyoutward. The outer shaft member 250 may thus be operatively coupled tothe rotation knob 260.

Referring now to FIG. 28, the rotational motion of the rotation knob 260is limited by its connection to a housing 302, which includes right andleft housing halves 302 a, 302 b, respectively. A stop 304 projectslaterally inward from housing half 302 b and is positioned to engage theproximal extension 280 to prevent rotational motion of the rotation knobfurther than, in one embodiment, 180 degrees in either direction. A pairof the detents 278 extending from outer circumference of the rotationknob 260 engage a pair of cantilever arms 306 projecting from thehousing half 302 b. The engagement of the detents 278 with thecantilever arms 306 defines a relatively stable relation between therotation knob 260 and the housing 302. In one embodiment, the detents278 are radially spaced by about 90 degrees such that at least threerelatively stable positions may be defined within the extent of therotation permitted by proximal extension 280 and the stop 304. Thesepositions may correspond to a configuration wherein jaw members 222 and224 (FIG. 22) curve to the left, in an upward direction, and to rightfrom the perspective of a user. The components for limiting the rotationof the rotation knob 260 are all defined on an interior of the housing302, and thus, interference from foreign materials is limited.

The outer shaft member 250, rotation knob 260 and the housing 302 definea longitudinal passage through which jaw drive rod 80, knife 102 andwire conduits 78 a and 78 b may extend. The rotation knob 260 may alsoinclude an interior shelf (not shown) against which spring 219 may becompressed (see FIG. 21D for a depiction of the spring 219 in acompressed state).

Referring now to FIG. 29, a knife carriage 310 may be operativelycoupled to the knife 102 by relative rotation of the knife carriage 310with respect to the knife. The knife carriage 310 includes a singlecomponent (compare with knife carriage 210 described above withreference to FIG. 19, which includes both a cap 218 and a sleeve 212 forcapturing the knife 102). An opening 312 in the knife carriage 310receives the proximal tabs 108 a, 108 b of the knife 102. Rotation ofthe knife carriage 310 in the direction of arrow Q1 captures theproximal tabs 108 a, 108 b against a proximal ledge of the knifecarriage. Thus, longitudinal motion may be transmitted between the knifecarriage 310 and the knife 102.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely as examplesof particular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A surgical instrument, comprising: a housing; anelongated shaft coupled to the housing and defining a longitudinal axis;a pair of opposing jaw members disposed at a distal portion of theelongated shaft, at least one of the pair of opposing jaw membersincluding a cam slot; and a drive rod having a generally u-shapedprofile and configured to move longitudinally within the elongated shaftto translate a cam pin through the cam slot to move at least one of thejaw members relative to the other jaw member.
 2. The surgical instrumentaccording to claim 1, wherein a first jaw member of the pair of opposingjaw members includes a first pair of laterally spaced flanges and asecond jaw member of the pair of opposing jaw members includes a secondpair of laterally spaced flanges, the first and second pairs of flangesarranged in an offset configuration such that one flange of the pair offlanges of the first jaw member is positioned on a laterally exteriorside of a corresponding flange of the pair of flanges of the second jawmember, and the other flange of the pair of flanges of the first jawmember is positioned on a laterally interior side of the other flange ofthe pair of flanges of the second jaw member.
 3. The surgical instrumentaccording to claim 2, wherein the drive rod is configured to movelongitudinally through a laterally interior side of each of the flanges.4. The surgical instrument according to claim 2, wherein each of thepairs of flanges extends proximally from a curved tissue engagingportion of each respective jaw member.
 5. The surgical instrumentaccording to claim 2, wherein the pair of opposing jaw members arepivotally coupled to the distal portion of the elongated shaft about apivot axis.
 6. The surgical instrument according to claim 5, wherein thepivot axis extends through each of the pairs of flanges transverse tothe longitudinal axis defined by the elongated shaft.
 7. The surgicalinstrument according to claim 2, wherein at least one of the flanges ofthe pair of flanges of each of the jaw members includes an electricallyisolative wire guide disposed on a lateral side thereof and configuredto receive an electrical wire.
 8. The surgical instrument according toclaim 7, wherein the wire guides are constructed of an electricallyisolative plastic.
 9. The surgical instrument according to claim 1,wherein the pair of opposing jaw members are disposed laterally offsetrelative to one another.
 10. The surgical instrument according to claim1, wherein the elongated shaft has a generally rectangular profile. 11.The surgical instrument according to claim 1, further comprising a knifeconfigured to move longitudinally within the drive rod.
 12. The surgicalinstrument according to claim 11, wherein the drive rod restrictslateral movement of the knife in a first lateral plane and a secondlateral plane that is orthogonal to the first lateral plane.
 13. Thesurgical instrument according to claim 11, wherein the drive rodincludes an overfold such that the drive rod surrounds the knife on fourlateral sides of the knife.